<article class="" id="post-">
<header class="entry-header">
<h1 class="entry-title">:first-child Selector</h1>
<div class="entry-meta">
						所属分类：<span class="category"><a href="/category/selectors/">选择器</a> &gt; <a href="/category/selectors/child-filter-selectors/">子元素过滤</a></span>
<span class="pull-right">英文文档：<a href="https://api.jquery123.com/first-child-selector/" target="_blank">:first-child Selector</a></span>
</div><!-- .entry-meta -->
</header><!-- .entry-header -->
<!-- .entry-header -->
<div class="entry-content">
<article class="entry selector" id="first-child1"><h2 class="section-title"><span>first-child selector</span></h2>
<div class="entry-wrapper">
<p class="desc"><strong>描述: </strong>选择所有父级元素下的第一个子元素。</p>
<ul class="signatures"><li class="signature"><h4 class="name">
<span class="version-details">添加的版本: <a href="/category/version/1.1.4/">1.1.4</a></span>jQuery( ":first-child" )</h4></li></ul>
<div class="longdesc" id="entry-longdesc">
<p>虽然<a href="/first-selector">:first</a>只匹配一个单独的元素，但是<code>:first-child</code>选择器可以匹配多个：即为每个父级元素匹配第一个子元素。这相当于<code>:nth-child(1)</code>。</p>
</div>
<section class="entry-examples" id="entry-examples"><header><h2 class="underline">例子:</h2></header><div class="entry-example" id="example-0">
<h4><span class="desc">给每个匹配的 div 中查找第一个 span，并加上下划线及增加鼠标悬停效果。</span></h4>
<div class="syntaxhighlighter xml ">
<table>
<tbody>
<tr>
<td class="gutter">
<div class="line n1">1</div>
<div class="line n2">2</div>
<div class="line n3">3</div>
<div class="line n4">4</div>
<div class="line n5">5</div>
<div class="line n6">6</div>
<div class="line n7">7</div>
<div class="line n8">8</div>
<div class="line n9">9</div>
<div class="line n10">10</div>
<div class="line n11">11</div>
<div class="line n12">12</div>
<div class="line n13">13</div>
<div class="line n14">14</div>
<div class="line n15">15</div>
<div class="line n16">16</div>
<div class="line n17">17</div>
<div class="line n18">18</div>
<div class="line n19">19</div>
<div class="line n20">20</div>
<div class="line n21">21</div>
<div class="line n22">22</div>
<div class="line n23">23</div>
<div class="line n24">24</div>
<div class="line n25">25</div>
<div class="line n26">26</div>
<div class="line n27">27</div>
<div class="line n28">28</div>
<div class="line n29">29</div>
<div class="line n30">30</div>
<div class="line n31">31</div>
<div class="line n32">32</div>
<div class="line n33">33</div>
<div class="line n34">34</div>
</td>
<td class="code">
<pre><div class="container"><div class="line"><code><span class="doctype">&lt;!DOCTYPE html&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">html</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">head</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">style</span>&gt;</span><span class="css"></span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">span</span> <span class="rules">{ <span class="rule"><span class="attribute">color</span>:<span class="value"><span class="hexcolor">#008</span>;</span></span> <span class="rule">}</span></span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">span</span><span class="class">.sogreen</span> <span class="rules">{ <span class="rule"><span class="attribute">color</span>:<span class="value">green;</span></span> <span class="rule"><span class="attribute">font-weight</span>:<span class="value"> bolder;</span></span> <span class="rule">}</span></span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;/<span class="title">style</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">script</span> <span class="attribute">src</span>=<span class="value">"https://code.jquery.com/jquery-latest.js"</span>&gt;</span><span class="javascript"></span><span class="tag">&lt;/<span class="title">script</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">head</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">body</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">div</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>    <span class="tag">&lt;<span class="title">span</span>&gt;</span>John,<span class="tag">&lt;/<span class="title">span</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>    <span class="tag">&lt;<span class="title">span</span>&gt;</span>Karl,<span class="tag">&lt;/<span class="title">span</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>    <span class="tag">&lt;<span class="title">span</span>&gt;</span>Brandon<span class="tag">&lt;/<span class="title">span</span>&gt;</span></code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;/<span class="title">div</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">div</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>    <span class="tag">&lt;<span class="title">span</span>&gt;</span>Glen,<span class="tag">&lt;/<span class="title">span</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>    <span class="tag">&lt;<span class="title">span</span>&gt;</span>Tane,<span class="tag">&lt;/<span class="title">span</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>    <span class="tag">&lt;<span class="title">span</span>&gt;</span>Ralph<span class="tag">&lt;/<span class="title">span</span>&gt;</span></code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;/<span class="title">div</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">script</span>&gt;</span><span class="javascript"></span></code></div></div><div class="container"><div class="line"><code>$(<span class="string">"div span:first-child"</span>)</code></div></div><div class="container"><div class="line"><code>    .css(<span class="string">"text-decoration"</span>, <span class="string">"underline"</span>)</code></div></div><div class="container"><div class="line"><code>    .hover(<span class="function"><span class="keyword">function</span> <span class="params">()</span> {</span></code></div></div><div class="container"><div class="line"><code>          $(<span class="keyword">this</span>).addClass(<span class="string">"sogreen"</span>);</code></div></div><div class="container"><div class="line"><code>        }, <span class="function"><span class="keyword">function</span> <span class="params">()</span> {</span></code></div></div><div class="container"><div class="line"><code>          $(<span class="keyword">this</span>).removeClass(<span class="string">"sogreen"</span>);</code></div></div><div class="container"><div class="line"><code>        });</code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">script</span>&gt;</span></code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">body</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">html</span>&gt;</span></code></div></div></pre>
</td>
</tr>
</tbody>
</table>
</div>
<h4>Demo:</h4>
<div class="demo code-demo"></div>
</div></section>
</div></article> </div>
</article>